What’s in the Dew? Abstract

Earth’s atmosphere is composed of a large variety of molecular compounds, including organics. Some of these organic compounds may be produced by human activity or vegetation on the earth’s surface. When organic material enters the atmosphere, some will condense to form aerosols while others will remain in the gas phase. These organics may then be oxidized to CO and CO2 or may be returned to the earth’s surface through wet and dry deposition. We do not know exactly how much carbon is lost from the atmosphere through deposition and what proportion of deposited carbon is then re-emitted into the atmosphere. The behavior of organics in the atmosphere has implications for earth’s climate and ecosystems, so it is important to understand the processes that affect carbon’s entrance and exit to and from the atmosphere. To investigate this problem, my summer research project will address two questions:

Aim 1: How do the absorption properties of dissolved organic matter in dew vary across different sample times and locations?

Aim 2: How rapidly does this organic mixture lose its color when exposed to sunlight?

By collecting dew samples and analyzing their contents, we can begin to form a picture of the organics the dew contains. When the dew is exposed to sunlight, the organic matter has the potential for further reactivity through dehydration and photolysis. Using UV-vis spectroscopy, which measures the compound’s absorption of light in the visible spectrum, I will analyze the reactivity of compounds in the dew before and after photolysis. The data I collect will give us information that will help characterize the reactivity of organic molecules found in surface water and will contribute to the body of knowledge being built by the O’Brien lab group.